'Q' Codes

The Q code is a standardized collection of three-letter codes all of which start with the letter "Q", a brevity code initially developed for commercial radiotelegraph communication, and later adopted by other radio services, especially amateur radio. Although Q codes were created when radio used Morse code exclusively, they continued to be employed after the introduction of voice transmissions. To avoid confusion, transmitter call signs are restricted; no country is ever issued an ITU prefix starting with "Q". Codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services.

Only a limited number of 'Q' codes were in use at Croydon these are listed below

QAA  Estimated position or time of arrival  QAB  Clearance to .......  QAC  A problem or emergency  QAD  Departed from  QAF  Advice place, time and altitude  QAH  What is your height  QAK  Is there any risk of collision  QAL  I am going to land at ....  QAN Advise surface wind direction and speed at your position  QBF  Are you flying in cloud  QBG  Altitude flying above cloud  QBH  Altitude flying below cloud  QBI  Fog regulations in force  QDM  Magnetic heading to steer to destination (no wind correction)  QFG  Overhead  QFH  Permission to descend below cloud  QFM  Maintaining flight level at (height)  QFO  Permission to land immediately  QFS  Request for radio facility to be in operation  QGE  Distance from transmission station  QGL  Request permission to enter control area  QGN  Request clearance to land  QGO  Permission to land denied  QGP  Number to land on  QSY  Change to another frequency  QTE  True bearing from station  QTF  Position of aircraft from bearings taken by D/F stations  QTH  What is your position